This invention relates generally to an insulating drainage device or system for use in removing water in the vicinity of foundations or the like as well as providing thermal insulation to the foundation.
In order to maintain basement interiors dry and moisture free, it is necessary to remove water penetrating the soil mass adjacent the subterranean walls quickly, while avoiding a decrease in the strength of the soil "piping" or pore pressure. Such removal is often accomplished hy means of drainage systems comprising drainage pipes surrounded by a mineral aggregate. The particle size distribution of the aggregate must be carefully matched to the native soil in the region of construction. The functions of a properly designed drainage system are to remove water from the surrounding soil while "filtering" preventing movement of soil particles therefrom. Many of the prior art drainage systems as discussed hereinabove suffer from significant deficiencies and disadvantages caused by clogging or other malfunctioning.
U.S. Pat. Nos. 3,563,038, 3,654,765 and 4,490,072 (all three prior patents being fully incorporated herein by reference) overcome the significant problems of prior art drainage systems by disclosing drainage devices of the type which include a drainage pipe provided below a core surrounded by a ground water previous material to provide a pathway for the water through the core into the drainage pipe. The drainage device disclosed in these three patents are well known by the terms subterranean wall drain, drainage system or composite curtain drain. Drainage systems of this type are commercially marketed by the ELJEN CORPORATION of Storrs, Conn. Typically, this drainage system comprises an envelope of a nonwoven filter material having a core which leads to a pipe inside the water previous nonwoven material. This core comprises a plastic sheet having a plurality of alternate valleys and raised portions defined in the sheet. Preferably, this core leads to a slotted pipe. During use, water enters the previous envelope material, flows downwardly along the corrugated hills and valleys of the plastic core material and then enters into the slotted pipe to be carried away from the hillside, foundation or filtration system. Thus, as so constructed, the drainage device of the prior patents are well adapted to handle the downward flow of water beneath the surface of the ground in a drainage system or a septic system filter such that normal hydrostatic pressure will force this water inwardly through the water permeable filter material and into the valleys defined in the core where gravity carries the water downwardly to the drainage pipe and more particularly to the slotted openings in the drainage pipe.
In an effort to improve the thermal insulative properties of buildings (so as to decrease energy costs), the construction industry routinely applies sheets of insulative material, typically polymeric foam sheets, to the outside foundation walls prior to backfilling. Generally, these foamed sheets (i.e., polyurethane) are adhesively applied to the cement or concrete foundation walls of the building. Often, a waterproofing material is applied between the foundation wall and the insulative sheets. This waterproofing material may consist of, for example, volclay panels, urethane modified tar coatings or adhesive backed rubber sheets.
While suitable for its intended purposes, one drawback of the drainage system disclosed in the three previously discussed patents is that little, if any, insulation is provided therefrom. In view of the widespread use of insulative sheets for foundation exteriors, there is a perceived need for providing a suitable water drainage system which also provides thermal insulation to the foundation, cellar wall or other retainer wall to which it is associated.
Presently, three separate layers are often used around the outside of foundation walls. The first layer comprises a waterproofing material applied on the foundation walls. This waterproofing material may consist of, for example, volclay panels, urethane modified tar coatings or adhesive backed rubber sheets. The second layer comprises the insulative sheet and the third layer comprises a suitable drainage system such as stone aggregate and pipe or the drainage system disclosed in the foregoing patents. Thus, these three separate layers entail three distinct labor intensive assemblies along with the purchasing and stocking of the various materials leading to high labor and purchasing costs.